Fiber optic switch actuator

ABSTRACT

An optical switch actuator moving an optical element into or out of an optical pathway. The optical element is coupled to a movable shuttle and driven by a motor between two rest positions. The motor includes two stationary coils and a magnet. The shuttle is magnetically latched in the rest positions. The optical element&#39;s position at the extended rest position is controlled with a stop that contacts the shuttle to provide accuracy and precision about multiple axes. The material used to construct the actuator&#39;s components aids in repeatedly positioning the optical element with precision.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a Continuation-In-Part of Ser. No.09/473,455, filed on Dec. 28, 1999.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not Applicable

BACKGROUND OF THE INVENTION

[0003] 1. Field of Invention

[0004] This invention pertains to an actuator for a fiber opticaldevice. More particularly, this invention pertains to an assembly thatlinearly moves an optical element into an optical path thereby alteringthe optical path.

[0005] 2. Description of the Related Art

[0006] In fiber optic networks, light signals are transmitted alongoptical fibers to transfer information from one location to another.Optical switches are used to selectively couple light from an inputfiber to an output fiber. Optical fibers typically have very smallcross-sections and narrow acceptance angles within which light enteringthe fiber must fall to promote efficient propagation of the light alongthe fiber. As such, optical switches must transfer light with precisealignment.

[0007] One type of electromechanical optical switch operates by moving amirror while maintaining the optic fibers and optical pathwaystationary. In response to electrical signals, a relay arm moves amirror into and out of an optical pathway. The relay arm moves themirror substantially parallel to its reflective surfaces. The travel ofthe relay arm along that axis is limited by stops that determine theposition of the mirror. The relay arm is constrained at the stops byonly a single contact point, thereby allowing inaccuracies in the radialposition due to rotation of the arm. Examples of such switches includeU.S. Pat. No. 5,133,030, issued to Lee on Jul. 21, 1992, entitled “FiberOptic Switch Having a Curved Reflector,” and U.S. Pat. No. 4,057,719,issued to Lewis on Nov. 8, 1977, entitled “Fiber OpticsElectro-Mechanical Light Switch.”

[0008] One problem with such a switch is that the relay mechanism maynot be able to provide the accuracy and precision in positioning themirror that may be required by some optical switching networks. Accuracyis the ability to achieve a desired position with any given movement.Precision is the ability to repeatedly achieve the same position over anumber of movements, regardless of where that position is located.Because the movement of the relay arm is constrained by only a singlepoint of contact with the stopper, the switch may only be able toprovide accurate alignment along a single axis (in the direction of thearm's movement). The use of a single contact point may result inposition inaccuracies due to the freedom of the relay arm to rotateabout additional axes. Furthermore, relay mechanisms are typicallyconstructed of materials that may be susceptible to significant wearfrom component contact through repeated use. Such material wear may leadto problems with precise placement of the mirror over time, in additionto position inaccuracies.

[0009] Another problem with electromechanical switches is that they usea large electromechanical actuator that may not permit the placement ofmirrors in the packing density that may be required for multiple switcharrays.

[0010] Other types of systems use electromagnetic actuators, forexample, disk drive systems. These systems typically use actuators toposition drive components over different regions of a disk. One problemwith such electromagnetic actuators is that they require a control servoloop in order to operate. With a servo loop, the position component mustbe actively adjusted to maintain proper positioning. As such, actuatorsof this type are unable to repeatedly return components to the sameposition when actuated, without the use of an active control loop. Thisadds complexity to a system's design and, thereby, may undesirablyincrease its cost.

BRIEF SUMMARY OF THE INVENTION

[0011] According to one embodiment of the present invention, an opticalswitch actuator is provided. The actuator includes an optical element, ashuttle, and a motor. The optical element, in one embodiment, includes amirror. The shuttle moves longitudinally within a cylinder, which has acylindrical stopper that contacts a flat on the shuttle, therebyprecisely locating the optical element in the extended position. Theshuttle is connected to the motor by a cable member. The motor includestwo stationary cored coils with a magnet that moves between the twocores. The magnet is attracted to the core, thereby latching the shuttlein either of two positions.

[0012] In one embodiment the shuttle, the cylinder sleeve it moveswithin, and the stopper are made of a close grained ceramic materialthat has low coefficient of thermal expansion, is not susceptible tocold metal bonding or welding, and exhibits little wear with repeateduse. The motor has a bearing and a bearing bushing made of the samematerial.

[0013] The stopper permits the optical element to have highrepeatability by stopping the shuttle at a fixed point and inhibitingthe shuttle from moving longitudinally and from moving about itslongitudinal axis. The optical element is attached to the shuttle withan adhesive with a low coefficient of thermal expansion and containsmicro-spheres, which allow the optical element to maintain alignmentonce positioned.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0014] The above-mentioned features of the invention will become moreclearly understood from the following detailed description of theinvention read together with the drawings in which:

[0015]FIG. 1 is a perspective view of an optical switch actuator;

[0016]FIG. 2 is a cross-sectional view of the actuator;

[0017]FIG. 3 is an exploded diagram showing the internal components ofthe actuator;

[0018]FIG. 4 is a schematic diagram of the actuator;

[0019]FIG. 5 is a cross-sectional view of the driven element of themotor;

[0020]FIG. 6 is an exploded view of the stopper and shuttle cylinder;and

[0021]FIG. 7 is a cross-sectional view of the stopper and shuttlecylinder.

DETAILED DESCRIPTION OF THE INVENTION

[0022] An apparatus for moving an optical element 132 between anextended position and a retracted position is disclosed. The apparatusis an optical switch actuator 10 suitable for use in optical switches.

[0023]FIG. 1 illustrates the actuator 10, which has a cylindrical body114 with electrical leads 142 a, 142 b, 142 c at one end and an opticalelement 132 at the opposite end. The optical element 132 has illustratedin the extended position. In the retracted position, the optical element132 is positioned closer to the end of the cylindrical body 114. A motorinside the cylindrical body 114 drives a shuttle 112, and the opticalelement 132, between the two positions. In one embodiment, the opticalelement 132 is a mirror. In another embodiment, the optical element 132is a filter. In one embodiment, a wavelength division multiplexed (WDM)switch made with an optical element 132 being a partially reflectivefilter. The use of optical elements, such as mirrors and filters, topropagate light between fiber collimators is well known in the art;according, a more detailed discussion of their operation is notprovided. As shown in FIG. 1, the optical element 132 is attached to theshuttle 112, which is constrained by a cover 104 and surrounded by atube 108.

[0024] The electrical leads 142 are attached to a flange 116 located atone end of the cylindrical body 114. The electrical leads 142 areconnected to a motor, or driver, in the cylindrical body 114. The motor,or driver, moves the shuttle 132 linearly between an extended positionand a retracted position. In the extended position, the optical element132 on the shuttle 132 interacts with an optical pathway and in theretracted position the optical element 132 is out of the opticalpathway.

[0025] Referring to FIG. 2, the motor includes a pair of electromagnets214, 212 and 224, 222 and a plunger assembly 232. A pair of electricalconductors 102 a, 102 b connect the upper winding 214 to two of theelectrical leads 142 a, 142 b and a second pair of electrical conductors104 a, 104 b connect the lower winding 224 to two of the electricalleads 142 b, 142 c. In one embodiment, the electrical conductors 102 a,102 b are lacquered to the cylindrical body 114. The electricalconductors 102 a, 102 b, 104 a, 104 b are connected to the electricalleads 142 by wrapping and then soldering the conductors 102 a, 102 b,104 a, 104 b to the appropriate lead 142. The upper and lowerdesignations are used only for convenience in referring to theorientation presented in the figures. Those skilled in the art willrecognize that the actuator 10 can be used in any orientation withoutdeparting from the spirit and scope of the present invention.

[0026]FIG. 2 shows the actuator 10 in cross-section. Inside thecylindrical body 114 is the motor assembly, which includes an upper coil214 wrapped around a hollow upper core 212, a lower coil 224 wrappedaround a hollow lower core 222, and a plunger, or plunger assembly, 232that moves between the upper core 212 and the lower core 222. Theplunger assembly 232 is attached to a wire 206 connected to the shuttle112. The plunger assembly 232 moves inside a bearing bushing 234.

[0027] The shuttle 112 moves within a cylindrical sleeve 202 between theextended and the retracted position. At the extended position, theshuttle 112 contacts a stopper 204, which prevents the shuttle 112 frommoving further in longitudinal direction. The stopper 204 determines theaccuracy with which the shuttle 112, and thereby the optical element132, can be positioned. However, the wear of the shuttle 112 may affectthe precision with which the optical element 132 can be repeatedlypositioned.

[0028] The shuttle 112, the cylindrical sleeve 202, and the stopper 204are constructed from a hard material having a small grain size, forexample, ceramic. Ceramic may be polished to higher degree than softermaterials such as plastics. When a material is polished, the grain sizeof the material determines its surface roughness and, thus, its surfacearea of contact. As a result, when materials come into contact with eachother, the area of contact is determined by the grain size of thecontacting materials. Materials having a small grain size will have agreater number of grain particles in contact with each other over agiven surface area. As such, a smaller grain size results in morecontact between the surface of the shuttle 112 and the cylindricalsleeve 202.

[0029] In one embodiment, for example, the grain size is approximatelyin the range of 0.3 to 0.5 microns and the distance of travel of shuttle112 is approximately 2 millimeters. When materials having this grainsize come into contact with each other, the contact accuracy may beapproximately 0.2 microns. Such a contact accuracy over a distance ofapproximately 2 mm results in an angular accuracy of approximately0.0001 radians.

[0030] The wear of the material results from the dislodging of surfacegrains, of which the size of the grains is one factor. The more grainsthat are dislodged, the greater the wear of the material. However, alarge force is required to dislodge a grain of any given size. A surfacematerial having a greater number of small gains will tend to have fewergains dislodged than a material having a fewer number of larger grains.As such, due to the larger number of grain contacts with small grainedsurfaces, less discernable wear may result than with a material having alarger grain size.

[0031] In another embodiment, other fine grained materials that reducewear on shuttle 112 and cylindrical sleeve 202 are used, for example,zirconia, silicon carbide, silicon nitride, and aluminum oxide. In yetanother embodiment, shuttle 112 and cylindrical sleeve 202 areconstructed from a metal or plastic material. If a larger grainedmaterial, such as a metal, is desired to be used, the speed at whichshuttle 112 is moved is slowed to prevent the generation of forces thatmay increase the wear on shuttle 112 and cylindrical sleeve 202.However, the use of ceramics provides greater precision and switchingspeed than is attainable with larger grained materials. As such, theproper selection of the material for shuttle 112 and cylindrical sleeve202 may aid in achieving a high precision and repeatability in thepositioning of optical element 132. Grain size, however, is only one ofseveral factors that may contribute to the wear resistance of amaterial. Other factors that may contribute to the wear resistance of amaterial include, for example, coefficients of friction, modulus ofrapture, tensile strength, compressive strength, and fracture toughness.The operation of such factors is well known in the art; accordingly, amore detailed discussion is not provided.

[0032] Actuator 10 is not limited to only having components constructedfrom the materials described above. In an alternative embodiment,shuttle 112 and cylindrical sleeve 202 are coated with the materialsdescribed above. For example, shuttle 112 and cylindrical sleeve 202 areconstructed of any rigid material and coated with a wear resistantceramic such as titanium nitride or aluminum oxide. The coating isapplied using techniques that are well known in the art, for example,chemical vapor deposition.

[0033] An advantage, other than wear resistance, to using a ceramicmaterial for the interface between the shuttle 112, the cylindricalsleeve 202, and the stopper 204 is that ceramic is not susceptible tocold-metal bonding or welding. Cold-metal bonding occurs when twocomponents in contact are placed under pressure, the more extreme thepressure, the greater the chance of cold-metal bonding occurring.Without cold-metal bonding, less motor power is required to overcomeinertia and start the plunger assembly 232 and the shuttle 112 moving.

[0034] The cylindrical sleeve 202 is aligned with the plunger assembly232 by the tube 108. The tube 108 has a central bore that is concentricwith the outside edge of its flange, which has the same diameter as thecylindrical body 114. The tube 108 is secured to the body 114 and thecylindrical sleeve 202 is secured to the inside of the tube 108. In oneembodiment adhesive is used to secure the tube 108 to the body 114 andthe sleeve 202 to the tube 108. In another embodiment, the tube 108 isnot used, and the cylindrical sleeve 202 is secured to the upper core212. In another embodiment, the upper core 212 has an alignment recessor groove into which the cylindrical sleeve 202 is secured, without thetube 108, by an adhesive.

[0035]FIG. 3 illustrates an exploded view of the internal components ofthe actuator 10. The shuttle 112, in one embodiment, is an MU ferrulethat is machined to have a first surface 336 for mounting the opticalelement 132 and a second surface 334 and an incline surface 332 forinterfacing with the cylindrical stopper 204. The wire 206 extends fromthe bottom of the shuttle 112 to the top portion of the shuttle 112. Inone embodiment, the wire 206 is secured to the shuttle 112 by anadhesive applied to the wire 206 before it is drawn into the shuttle112.

[0036] The optical element 132 is secured to the first surface 336 withan adhesive. The optical element 132 attachment to the shuttle 112,along with the repeatability of the shuttle 112 location in the extendedposition, is critical. The precise alignment of the optical element 132relative to the cylindrical body 114 is critical. Any misalignment canresult in an attenuation of the optical signal or the loss of thesignal. By matching the coefficient of thermal expansion of theindividual components and adhesives, the components of the actuator 10remain in alignment over a wide temperature range such that the opticalpath does not suffer degradation as the temperature varies. In oneembodiment, the temperature range is from −40° to +85° Centigrade. Inanother embodiment, the transition point of the adhesive is outside theoperating temperature range, which enhances the dimensional stability ofthe connection of the optical element 132 to the first surface 336. Inone embodiment, keeping the transition point outside the operating rangeis accomplished by using fillers. In still another embodiment, theadhesive has limited shrinkage, which can be accomplished with a filler.Further, the adhesive can be cured in place. In one embodiment theadhesive is cured by ultraviolet light.

[0037] In one embodiment the adhesive is a quick curing adhesive blendedwith amorphous silica spheres of a selected diameter. The adhesive iscompressed between the optical element 132 and the first surface 336,with the spheres forming a monolayer, which results in dimensionalstability when the adhesive is cured. In another embodiment the adhesiveis Dymax OP66LS, which has a coefficient of thermal expansion similar tothat of the shuttle 112 such that the optical element 132 remains inalignment as the temperature varies within the operating range of theactuator 10.

[0038] In addition to the adhesive, the repeatability of the opticalelement 132 location relative to the cylindrical body 114 is achieved bythe stopper 204 contacting the incline surface 332, which makes theshuttle 112 self-aligning. The stopper 204 is fixed in position by thecover 104 and the cylindrical sleeve 202. The stopper 204 contacts theincline surface 332 of the shuttle 112 which stops the shuttle 112 fromextending further. Also, the stopper 204, by its length contacting thewidth of the incline surface 332, prevents the shuttle 112 from rotatingwithin the cylindrical sleeve 202 in the fully extended position.Therefore, the interaction of the stopper 204 and the incline surface332 serve to ensure that the optical element 132 position is highlyrepeatable when in the extended position.

[0039]FIG. 5 illustrates the plunger assembly 232 which is shown betweenthe upper coil core 212 and the lower coil core 222 shown on FIG. 3. Theplunger assembly 232 includes an upper armature 314 and a lower armature320. Sandwiched between the upper and lower armatures 314, 320 are apermanent magnet 318 and a bearing 316. The bearing 316 is ring shapedand has an inside diameter greater than the outside diameter of thepermanent magnet 318. The bearing 316 has an outside diameter greaterthan that of the upper and lower armatures 314, 320 and slightly lessthan the inside diameter of the bearing bushing 234. The outside edge ofthe bearing 316 slides along the inside surface of the bearing bushing234. Both the bearing 316 and the bearing bushing 234, in oneembodiment, are constructed from a hard material having a small grainsize, for example, ceramic, as described above for the shuttle 112 andthe cylindrical sleeve 202.

[0040] The plunger assembly 232 is held together by the central plunger324, which has the wire 206 in its center. The central plunger 324 fitsin a central opening in the upper and lower armatures 314, 320,permanent magnet 318, the upper washer 312 and the lower washer 322. Inone embodiment, the central plunger 324 is sized for an interference fitwith the central opening and is pressed into the openings, therebysecuring the assembly 232. In another embodiment, the central plunger324 is secured in the openings by an adhesive. In still anotherembodiment, the central plunger 324 is positioned in the openings andpressure is applied to its exposed ends, causing the central plunger 324to expand.

[0041] The upper and lower washers 312, 322, in one embodiment, areconstructed of a resilient material, such as nylon or an elastomer. Inanother embodiment, the washers 312, 322 are non-metallic. Resilientwashers 312, 322 act as shock absorbers; thereby aiding in the long lifeof the actuator 10 by avoiding slamming the shuttle 112 into the stopper204. The actuation pressure of the assembly 324 against the cores 212,222, if the contact surfaces are metalto-metal, can cold-weld thecontact surface to each other. Resilient or non-metallic washers 312,322 avoid cold-welding or sticking of the assembly 324 to the upper andlower cores 212, 222.

[0042]FIG. 4 illustrates the electrical schematic of the actuator 10. Inoperation, a direct current voltage is momentarily applied to electricalleads 142 a, 142 b, which energizes the upper coil 214 and causes thepermanent magnet 318 to be attracted to the upper core 212. The movementof the permanent magnet is shown by the arrow 412 on FIG. 4. The voltagepulse causes the permanent magnet 318, and the plunger assembly 324, tomove toward the upper core 214 and when the permanent magnet 318 is nearthe upper core 214, magnetic attraction latches the plunger assembly 324in the extended position. The plunger assembly 324 is connected to theshuttle 112 via the wire 206. The shuttle 112 is constrained fromextending by the stopper 204, which ensures that the shuttle 112 stopsat the same point each time it is in the extended position. With theshuttle 112 constrained by the stopper 204 and the wire 206 beingstraight, the plunger assembly 324 does not make contact with the uppercore 212. However, as the plunger assembly 324 moves between its twopositions, the wire 206 flexes. This flexing serves to minimize anyshock transmitted to the optical element 132 from the plunger assembly324. In one embodiment, the wire is coated with a slick material, suchas Teflon, so that, if the wire were to contact the inside surface ofthe upper core 212, the wire will slide with minimum friction.

[0043] A direct current voltage pulse applied to electrical leads 142 b,142 c momentarily energizes the lower coil 224 and causes the permanentmagnet 318 to be attracted to the lower core 222. The magnetic forceinduced in the lower core 222 overcomes the magnetic attraction of thepermanent magnet 318 to the upper core 212 and causes the plungerassembly 232 to move toward the lower core 222. When the permanentmagnet 318 approaches the lower core 222, the magnetic attraction to thelower core 222 pulls the plunger assembly 324 toward the core 222 untilthe lower washer 322 contacts the lower core 222. With the opticalelement 132 in the retracted position, the plunger assembly 324 islatched against the lower core 222 by the magnetic attraction of thepermanent magnet 318 to the lower core 222. In one embodiment, theplunger assembly 232 is in contact with the core 212, 222. In anotherembodiment, there is an air gap between the plunger assembly 232 and thecore 212, 222. In still another embodiment, a gap is created by the useof non-ferromagnetic washers 312, 322. The use of a gap reduces thepower required for the coils 214, 224 to move the plunger assembly 232.

[0044] In another embodiment, a direct current pulse is applied to onecoil 214 or 224 to attract the permanent magnet 318 and another pulse isapplied to the other coil 224 or 214 to repulse the permanent magnet318. The polarity of the voltage applied to the coils 214, 224 isreversed to move the plunger assembly 232 in the opposite direction.This has the effect of having one coil 214 or 224 attracting thepermanent magnet 318 and the other coil 224 or 214 pushing the permanentmagnet 318, thereby requiring less power to move the plunger assembly232 between its two positions.

[0045] Position indication of the plunger assembly 324, and the opticalelement 132, is achieved by measuring the inductance of each of thecoils 214, 224. The plunger assembly 324 has two possible positionscorresponding to the optical element 132 being extended and retracted:with the optical element 132 extended, the assembly 324 is adjacent theupper core 212 and with the optical element 132 retracted, the assembly324 is adjacent the lower core 222. The coil that the permanent magnet318 is closest will have a different inductance than the other coil. Inone embodiment, the relative inductance is measured by connecting thecoils to a circuit that responds to changes in inductance and thatresponds to a measured inductance above or below a predeterminedthreshold value.

[0046]FIG. 6 illustrates the cylindrical sleeve 202, the stopper 204,and the cover 104. FIG. 7 is a cross-sectional view of the same threecomponents. The stopper 204 is a rod-shaped member that rests in a notchcut in the cylindrical sleeve 202 and is held in position by the cover104. In one embodiment, the stopper 204 is fixedly held in position whenthe cover 104 is attached to the cylindrical sleeve 202. In anotherembodiment, the stopper 204 is loosely held in position and when theshuttle 112 is in the extended position, the incline surface 332 forcesthe stopper 204 upwards and away from the longitudinal axis of thecylindrical sleeve 202 until the stopper 204 is wedged between the cover104, the notch cut in the cylindrical sleeve 202, and the inclinesurface 332. The repeatability of the shuttle 112 in the extendedposition is assured by the stopper 204 contacting the cover 104 and thecylindrical sleeve 202 and by the incline surface 332 of the shuttle 112contacting the stopper 204 and having the shuttle 112 rotate within thecylindrical sleeve 202 such that the incline surface 332 aligns with thestopper 204. This alignment function eliminates the need for tighttolerance between the shuttle 112 and the cylindrical sleeve 202 andresults in the shuttle 112 returning to the same extended positionduring repeated operations with little spatial deviation.

[0047] The ends of the stopper 204 do not extend past the outsidecylindrical surface of the cylindrical sleeve 202. The cover 104 fitsover the end of the cylindrical sleeve 202. In one embodiment, the cover104 is sized for an interference fit with the cylindrical sleeve 202 andthe cover 104 is pressed onto the end of the cylindrical sleeve 202,thereby securing the stopper 204 in a fixed position. In anotherembodiment, the cover 104 is secured in place with an adhesive.

[0048] From the foregoing description, it will be recognized by thoseskilled in the art that an actuator 10 for linearly moving an opticalelement 132 has been provided. The actuator 10 has opposed coils 214,224 that force a magnet 318 to move between two positions. The magnet318 movement is translated to a shuttle 112 with the optical element132. The shuttle 112 engages a stopper 204 at the extended position,which causes the shuttle 112 to stop at a fixed point with highrepeatability. The stopper 204 prevents the shuttle 112 from movinglongitudinally along the longitudinal axis. The stopper 204 alsoprevents the shuttle 112 from rotating about the longitudinal axis.Polishing the inside of the sleeve 202 and the shuttle 112 allows forlow friction motion of the shuttle 112. Polishing the inside of thebearing bushing 234 and the outside surface of the bearing 316 allowsfor low friction motion of the plunger assembly 232. The low thermalexpansion of the ceramic materials, along with the low friction surfacesand the self-aligning shuttle 112, results in high repeatability andeasier alignment of the optical element 132 within an optical pathway.

[0049] While the present invention has been illustrated by descriptionof several embodiments and while the illustrative embodiments have beendescribed in considerable detail, it is not the intention of theapplicant to restrict or in any way limit the scope of the appendedclaims to such detail. Additional advantages and modifications willreadily appear to those skilled in the art. The invention in its broaderaspects is therefore not limited to the specific details, representativeapparatus and methods, and illustrative examples shown and described.Accordingly, departures may be made from such details without departingfrom the spirit or scope of applicant's general inventive concept.

Having thus described the aforementioned invention, we claim:
 1. Anactuator for interacting with an optical pathway, said actuatorcomprising: a body having a longitudinal axis and a first end; a firstelectromagnet in said body; a second electromagnet in said body; aplunger positioned inside said body between said first electromagnet andsaid second electromagnet, said plunger constrained to move along saidlongitudinal axis between said first electromagnet and said secondelectromagnet; a shuttle attached to said plunger, said shuttle having afirst surface, said shuttle movable between an extended position and aretracted position; a sleeve in fixed relation to said first end of saidbody, said sleeve having an inside surface, said shuttle in slideablecommunication with said inside surface; a stopper in fixed relation tosaid sleeve, said stopper positioned to contact said first surface ofsaid shuttle with said shuttle in said extended position whereby saidshuttle is constrained from moving along said longitudinal axis and fromrotating within said sleeve; and an optical element attached to saidshuttle.
 2. The actuator of claim 1 wherein said stopper is cylindrical.3. The actuator of claim 1 wherein said inside surface of said sleeveand an outside surface of said shuttle have a small grain size.
 4. Theactuator of claim 1 wherein said sleeve and said shuttle are constructedof a ceramic material.
 5. The actuator of claim 4 wherein said ceramichas a small grain size whereby an interface between said inside surfaceof said sleeve and an outside surface of said shuttle exhibits minimalwear.
 6. The actuator of claim 1 wherein said plunger assembly includesa permanent magnet.
 7. The actuator of claim 1 further including a wireconnecting said plunger to said shuttle.
 8. The actuator of claim 7wherein said wire has a non-stick coating.
 9. The actuator of claim 1wherein said actuator includes a means for latching said plunger at eachof a first position and a second position.
 10. The actuator of claim 1further including a bearing bushing and wherein said plunger assemblyincludes a bearing, said bearing in slideable communication with saidbearing bushing.
 11. The actuator of claim 10 wherein said bearingbushing and said bearing are constructed of a small grain size material.12. The actuator of claim 1 wherein said optical element is attached tosaid shuttle with an adhesive.
 13. The actuator of claim 12 wherein saidadhesive has a low coefficient of thermal expansion.
 14. The actuator ofclaim 12 wherein said adhesive has a coefficient of thermal expansionthat is substantially the same as a coefficient of thermal expansion ofsaid shuttle.
 15. The actuator of claim 12 wherein said adhesive has atransition point outside a range of −40° to +85° Centigrade.
 16. Theactuator of claim 12 wherein said adhesive contains a plurality ofmicro-spheres having a substantially uniform size.
 17. An actuator forinteracting with an optical pathway, said actuator comprising: a shuttlemovable between an extended position and a retracted position; anoptical element attached to said shuttle, whereby said optical elementinteracts with the optical pathway with said shuttle in said extendedposition; a driver moving said shuttle between said extended positionand said retracted position; and a stopper engaging said shuttle whensaid shuttle is in said extended position, said stopper constrainingsaid shuttle from moving along a longitudinal axis and from rotatingabout said longitudinal axis.
 18. The actuator of claim 17 wherein saiddriver includes a first electromagnet; a second electromagnet; and aplunger positioned between said first electromagnet and said secondelectromagnet, said plunger constrained to move between said firstelectromagnet and said second electromagnet, said plunger connected tosaid shuttle, whereby said plunger causes said shuttle to move betweensaid extended position and said retracted position.
 19. The actuator ofclaim 18 wherein said plunger includes a permanent magnet.
 20. Theactuator of claim 18 further including a wire connecting said plunger tosaid shuttle.
 21. The actuator of claim 18 further including a wireconnecting said plunger to said shuttle wherein said wire has anon-stick coating.
 22. The actuator of claim 18 further including aresilient material located between said plunger and said firstelectromagnet.
 23. The actuator of claim 18 further including aresilient material located between said plunger and said secondelectromagnet.
 24. The actuator of claim 17 wherein said stopper ispositioned to contact a surface of said shuttle with said shuttle insaid extended position whereby said shuttle is constrained from movingalong said longitudinal axis and from rotating about said longitudinalaxis.
 25. The actuator of claim 17 further including a sleeve in whichsaid shuttle is in slideable communication, said shuttle and said sleeveeach having an interface surface that has a small grain size.
 26. Theactuator of claim 17 further including a sleeve in which said shuttle isin slideable communication, said shuttle and said sleeve each having aninterface surface that is a ceramic material.
 27. The actuator of claim17 wherein said stopper is cylindrical.
 28. The actuator of claim 17wherein said optical element is attached to said shuttle with anadhesive.
 29. The actuator of claim 28 wherein said adhesive has a lowcoefficient of thermal expansion.
 30. The actuator of claim 28 whereinsaid adhesive has a coefficient of thermal expansion that issubstantially the same as a coefficient of thermal expansion of saidshuttle.
 31. The actuator of claim 28 wherein said adhesive has atransition point outside a range of −40° to +85° Centigrade.
 32. Theactuator of claim 28 wherein said adhesive contains a plurality ofmicro-spheres having a substantially uniform size.
 33. An actuator forinteracting with an optical pathway whereby an optical element is fixedto a shuttle that moves longitudinally within a sleeve, said actuatorcomprising a means for moving the shuttle between an extended positionand a retracted position; a means for latching the shuttle at each ofsaid extended position and said retracted position; and a means forstopping the shuttle at said extended position whereby the shuttle isconstrained from moving along a longitudinal axis and from rotatingwithin the sleeve.
 34. The actuator of claim 33 further including ameans for minimizing wear between the shuttle and the sleeve.
 35. Theactuator of claim 33 further including a means for attaching the opticalelement to the shuttle whereby said optical element is fixedlypositioned relative to the shuttle over a selected temperature range.